Dichlorodiphenyltrichloroethane (DDT)


Chemical Formula: C14 H9 Cl15
DDT_chemical_structure_highres.png
The chemical structure of Dichlorodiphenyltrichloroethane (DDT)


Uses of DDT: Although first synthesized in 1874, the use of DDT as an insecticide was not discovered until 1939 and it was used successfully during the second half of World War II to control the spread of typhus and malaria among the civilians and troops.
In 1945, DDT was made available to farmers as an agricultural insecticide. DDT was also used to eradicate malaria in places like Taiwan, the Caribbean, the Balkans, parts of Northern Africa, the northern region of Australia, and a large swath of the South Pacific.

Health Hazards: DDT is classified as "moderately toxic" by the United States National Toxicology Program (NTP) and "moderately hazardous" by the World Health Organization (WHO). DDT carries a large number of side effects that effect numerous parts of the body. They include but are not limited to:
  • Dizziness
  • Tremors
  • Irritability
  • Convulsions
  • Lasting neurological and cognitive problems
  • Premature births
  • Small-for-gestational-age babies
  • May cause cancer
  • May cause diabetes
  • Parkinsons disease
  • Asthma
  • Other health issues due to DDT's estrogen-like properties

Efforts to Curb DDT: As early as the 1940s, scientists in the U.S. began to question the health hazards of DDT, but it was not until the 1950s that the government began to tighten their regulations about the use of DDT. In 1962, an author named Rachel Carson published a book titled "Silent Spring," which argued that pesticides, including DDT, were poisoning the enviroment and the wildlife and affecting human health. The book was a best-seller and jumpstarted and enviromental movement in the U.S. The year after, President Kennedy ordered an investigation on Carson's claims. Investigations revealed that pesticides were indeed poisoning the enviroment and killing wildlife, but it was not until the summer of 1972 that the government banned DDT, except for special public health uses. Several countries followed suit, including Hungary in 1968, Norway and Sweden in 1970, Germany in 1972, and the United Kingdom in 1984

After the Ban: Some uses of DDT continued after the U.S. ban. In 1979, the California Department of Health Services was allowed to use DDT to supress flea vectors of bubonic plague. Over 300 tonnes were exported from the U.S. to foreign markets until as late as 1985. Despite the worldwide ban, agricultural use continues in India, North Korea, and possibly elsewhere. Currently, about three to four thousand tonnes of DDT are produced each year for vector control. DDT is applied inside walls of homes to kill or repel mosquitoes.

How to Limit Exposure: Since DDT is illegal, it is not very common in Canada. So the only thing you can do to limit exposure is to try to avoid eating foods from countries where DDT use is still legal.